What is the ruling on breaking the fast for someone who vowed to fast a month and was blessed with a healthy child, then was compelled to break the fast due to surgery? And is feeding the poor sufficient as expiation for the remaining days? And is it permissible to give the expiation in another country?

A vow contingent on a disliked condition is disfavored, but it becomes obligatory to fulfill if the condition it was made contingent upon occurs. Therefore, you must fast the month you vowed, whether consecutively or separately. Since you have not fasted a month by lunar reckoning, you must fast thirty days, and complete the remaining fast after recovering from the surgery.